#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main() {
    int n, d;
    cin >> n >> d;
    map<int, ll> l, r;
    vector<int> a(n);
    rep(i, n) cin >> a[i];
    rep(i, n) {
        r[a[i]]++;
    }
    ll ans = 0;
    rep(i, n) {
        r[a[i]]--;
        ans += l[a[i] - d] * r[a[i] + d];
        l[a[i]]++;
    }
    cout << ans << endl;
    return 0;
}